leaders about the civil war still raging in syria. reports say clashes between government forces and rebels are flaring around the capital of damascus. >> concerns are escalating abut possible use of chemical weapons, a step president obama warned syria not to take. abc's martha raddatz has more. >> reporter: hillary clinton overseas trying to find some diplomatic way to end this increasingly dangerous conflict. 20 months of fighting, 40,000 lives lost, and now the chilling possibility of an air attack with deadly nerve agents. >> there is no question that we remain very concerned that the regime might very well consider the use of chemical weapons. >> reporter: a senior u.s. official saying over the weekend the syrian military loaded components of the nerve gas sarin into bombs on or near syrian airfields. they have not loaded the bombs on to aircraft, but the threat remains. >> once the chemicals are poured into weapons, artillery shells, bombs that can be dropped from airplanes they can be good up to two months. >> reporter: the sy